The present invention relates to apparatus and methods for stabilizing earthen retaining walls or embankments.
It is well known in the prior art to stabilize earthen embankments with supports and associated geogrids extending rearwardly from the support into the stabilized embankment. This includes embankments with a slope of less than 90 degrees and embankments with a 90 degree slope. In cases where flexible fiber geogrids are used, the geogrid often is wrapped over the face of the support and under the floor of the support But, the time and labor required to instal such geogrids is substantial.
Flexible fiber geogrids are available from various sources, for example, Strata Systems, Inc. of Cumming, Ga., U.S. who provide a family of high strength polyester yarn geogrids for soil reinforcement.
U.S. Pat. No. 5,975,810 (Taylor et al.) granted on Nov. 2, 1999 discloses apparatus for securing a flexible fiber geogrid to a support without wrapping over the face of the support. In a number of embodiments there is a need to carefully fold the forward end portion of the geogrid back and forth in layers upon itself to provided improved shear strength. The layered end portion is then secured with a retaining rod which is positioned to press against the layers—in effect sandwiching the layers between the rod and the underlying support on which the layers are positioned. In the field, the required aligned folds may be considered awkward and time consuming to achieve. Further, the anchorage does not have a positive hold on the geogrid. The integrity of the anchorage when the geogrid is tensioned appears to be largely dependent upon the compressive grip which the retaining rod imposes on the folded layers. In another embodiment, Taylor et al. describe anchoring a geogrid by means of a retaining rod around which the forward end of a geogrid is folded 180 degrees backwards. However, by itself, the rod does not provide a positive hold on the geogrid. The geogrid is restrained only by the resistance of backfill which is required to be placed over the folded end portion of the geogrid before tension is applied to the geogrid. The sufficiency of the restraint will be dependent on the length of the folded end portion and frictional characteristics of the backfill, the latter of which may vary depending on dampness and other factors. To adjust for such considerations will require particular skill and expertise on the part of those determining what length a folded portion should have to achieve a desired connection strength.
Accordingly, there is a need to provide apparatus and a method for positively anchoring a flexible fiber geogrid to a support with a strong, reliable connection which requires minimal labor.